This application incorporates by reference of Taiwan application Serial No. 90104273, filed on Feb. 23, 2001.
1. Field of the Invention
The invention relates in general to a liquid crystal display (LCD) capable of being repaired and method for repairing the same, and more particularly to a LCD capable of being repaired for detects in data lines and method for the same.
2. Description of the Related Art
Liquid crystal displays are widely used because of having low radiation and compactness. For high-end products, thin film transistor LCDs (TFT-LCDs) are employed due to high brightness and wide view angles. In order to make products more competitive, manufacturers make efforts in the increase in yields and the reduction in cost.
A conventional TFT-LCD has a front plate and a rear plate. The front plate includes a number of transparent pixel electrodes, color filters, and black matrices. The rear plate includes a number of scan lines, data lines, storage capacitors, switching elements (e.g., TFTs), and transparent pixel electrodes.
FIG. 1 illustrates a pixel layout of a conventional TFT-LCD. The TFT-LCD has a number of scan lines 102 and data lines 104 perpendicularly intersecting the scan lines 102, thus forming a number of pixel regions. Each of the pixel regions is defined by a corresponding scan line and data line. Each pixel region includes a storage capacitor Cs, a TFT, and a transparent pixel electrode 106. The TFT is formed with a drain electrode G, a drain electrode D, and a source electrode S, and a channel 110. The scan lines 102 are connected to the gate electrodes of the TFTs while the data lines 104 are connected to the drain electrodes of the TFTs. The transparent pixel electrode 106 is coupled to the source electrode of the corresponding TFT.
FIG. 2 is a cross-sectional view taken along line AAxe2x80x2 of FIG. 1. Referring to FIGS. 1 and 2, a conventional method for manufacturing a TFT is described below.
First, after a plate 202 is provided, a first metal layer is formed and then patterned to form a gate electrode G. Next, an isolation layer 204 is formed on the plate 202 and is used to cover the gate electrode G. An amorphous-Si (a-Si) layer is formed on the isolation layer 204 and then patterned to form the channel 110. After that, a second metal layer is formed, covering the channel 110 and the isolation layer 204. By performing a photolithography process on the second metal layer, the drain electrode D and the source electrode S are formed. Next, a protection layer 206 is formed on the drain electrode D and source electrode S so as to cover the isolation layer 204. The contact 108 is then formed within the protection layer 206, thus causing the protection layer 206 to expose the source electrode S through the contact 108. Finally, the transparent pixel electrode 106 is formed over the protection layer 206 and fills the contact 108 so that the transparent pixel electrode 106 is electrically coupled to the source electrode S.
The scan lines 102 and data lines 104 are respectively formed during the patterning of the gate and the source/drain (S/D) electrodes. The isolation layer 204 is used to separate the scan lines 102 and data lines 104.
FIG. 3 is a cross-sectional view taken along line BBxe2x80x2 of FIG. 1. With reference to FIGS. 1, 2, and 3, a conventional method for manufacturing a storage capacitor is described below.
A storage capacitor Cs is formed with a common electrode 112 and a capacitor electrode 114 while the common electrode 112 and capacitor electrode 114 are separated by the isolation layer 204. The storage capacitor Cs is formed together with the formation of the TFT. The common electrode 112 is formed after the formation and patterning of the first metal layer. Likewise, after the formation and patterning of the second metal layer, the capacitor electrode 114 is formed. The protection layer 206 covers the capacitor electrode 114 and the isolation layer 204. A contact 116 is formed within the protection layer 206. When the transparent pixel electrode 106 is formed over the protection layer 206, the transparent pixel electrode 106 and the capacitor electrode 114 are electrically coupled through the contact 116. In addition, storage capacitors of all pixels of the TFT-LCD have their common electrodes connected to a common voltage of the TFT-LCD.
Unfortunately, defects may occur during the manufacturing of the common electrodes of the storage capacitors Cs and thus degrade the quality of the TFT-LCD. For example, when cracks or undesired particles occur on the plate 202, the common electrode 112 is formed with defects. In the worst case, the common electrode 112 may be disconnected due to serious defects. In additional, the common electrodes of all the storage capacitors Cs are coupled to the respective scan lines 102. Therefore, when disconnection occurs in one of the common electrodes, such as the common electrode 112, the other common electrodes that share the identical scan line with the common electrode 112 would have their signal path opened so that their associated storage capacitors cannot operate. In another case, defects that occur in the isolation layer 204 of the storage capacitor Cs due to undesired particles on the plate 202 during the manufacturing process may result in the capacitor electrode 114 and the common electrode 112 short-circuited. If the two electrodes are short-circuited, a signal on one scan line associated with the short circuit will interfere with the common electrodes on the scan line and the storage capacitors Cs on the same scan line cannot operate properly.
A conventional approach to solving the problems due to the defects is to break the connection of the TFT and the transparent pixel electrode of a pixel having a malfunctioned storage capacitor Cs so as to prevent the short-circuited common electrode 112 from affecting the other storage capacitors along the associated scan line. However, the pixel associated with the malfunctioned storage capacitor Cs cannot be lighted.
In addition, disconnection may also occur in the data lines 104 due to defects or notching occurred during the formation of the data lines 104 by patterning the second metal layer. When the disconnection of the data lines 104 occurs, the data lines 104 operate improperly. In the worst case, the entire rear plate of the LCD may be useless due to serious disconnection of the data lines 104. Conventionally, repair cannot be made directly on the rear plate where the disconnection of the data lines 104 occurs. To compensate for the problem due to the disconnection of the data lines 104, operations performed by a control circuit of the rear plate should be particularly designed. However, the control circuit can only be designed to perform compensating operations on a limited number of data lines disconnected. If an increased number of disconnected data lines are required, the cost of the control circuit for the requirement increases correspondingly.
It is therefore an object of the invention to provide a liquid crystal display (LCD) capable of being repaired for defects in data lines and storage capacitors of the LCD, and a method for repairing the same. According to the invention, at least two storage capacitors are employed in each pixel, a first and a second ring-type conductors are connected and formed between two adjacent scan lines and correspond to the data line associated with the pixel. The problems due to the defects in data lines and storage capacitors of the LCD can be resolved. In addition, the LCD has an increased yield and a reduced cost.
The invention achieves the above-identified object by providing a liquid crystal display capable of being repaired for defects in data lines. The liquid crystal display includes multiple scan lines, multiple data lines, multiple transparent pixel electrodes, multiple switching devices, multiple first storage capacitors, multiple second storage capacitors, multiple first ring-type conductors, and multiple second ring-type conductors. The data lines intersect the scan lines in perpendicular substantially while the scan lines and the data lines define a number of pixel regions, wherein each of the pixel regions is defined by a pair of the scan lines and a pair of the data lines. Each of the transparent pixel electrodes is disposed within the pixel regions respectively. The switching devices correspond to the pixel regions respectively, and each of the switching devices is connected to a corresponding one of the data lines and a corresponding one of the scan lines. Each of the first storage capacitors is disposed within one of the pixel regions, and includes a first capacitor electrode and a first common electrode. Each of the first capacitor electrodes is connected to a corresponding one of the transparent pixel electrodes. Each of the second storage capacitors is disposed within one of the pixel regions, and includes a second capacitor electrode and a second common electrode. Each of the second capacitor electrodes is connected to a corresponding one of the transparent pixel electrodes. Each of the first ring-type conductors is disposed between two adjacent scan lines of the scan lines and corresponds to one of the data lines. In addition, each of the first ring-type conductors is coupled to the first common electrode of two adjacent pixel regions of the pixel regions, and insulatingly intersects corresponding data lines at a first intersection and a second intersection in perpendicular substantially. Each of the second ring-type conductors is disposed between two adjacent scan lines of the scan lines, and corresponds to one of the data lines. In addition, each of the second ring-type conductors is coupled to the second common electrode of two adjacent pixel regions of the pixel regions, and insulatingly intersects corresponding data lines at a third intersection and a fourth intersection in perpendicular substantially.
The invention achieves the above-identified object by providing a method for repairing the liquid crystal display with defects in data lines. The method includes the following steps. First, when one of the data lines has a defect, the first ring-type conductor that surrounds the defect is selected. The first ring-type conductor that surrounds the defect is coupled to the data line at the first and second intersections corresponding to the data line and the first ring-type conductor that surrounds the defect. Next, a portion, between the first and second intersections corresponding to the data line and the first ring-type conductor that surrounds the defect, of the first ring-type conductor that surrounds the defect is isolated from the other portion thereof the first ring-type conductors other than the first ring-type conductor that surrounds the defect, and the second ring-type conductors.
The invention achieves the above-identified object by providing a method for repairing the liquid crystal display with defects in storage capacitors. The method includes the step of when one of the first storage capacitor has a defect, isolating the first common electrode of the first storage capacitor that has the defect from the first ring-type conductors and the second ring-type conductors.
Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description of the invention is made with reference to accompanying drawings.